The research project proposes a study of those primary transcription products of the herpes simplex virus genome, and their post-transcriptional modifications yielding a limited number of cytoplasmic mRNA species (e.g. "alpha mRNA"). Two experimental approaches will be used to identify and characterize nuclear precursors: 1) hybridization of pulse-labelled RNA to restriction fragments of viral DNA ("nascent chain" experiments) and 2) use of inhibitors of RNA metabolism to either block transcriptional or post-transcriptional events.